Fluid-cooled electric discharge device



July 4, 1950 K. c. DE WALT Fwmcoomn ELECTRIC DISCHARGE DEvIcE Filed Aug.14, 1947 Ihventor: Kenneth C. DeWalt, bgm'zm His Attorneg.

Patented July 4, 1950 FLUID-COOLED ELECTRIC DISCHARGE DEVICE Kenneth C.De Walt, Scotia, N. Y., assignor to General Electric Company, acorporation of New York Application August 14, 1947, Serial No. '768,697

Claims. (Cl. Z50-27.5)

My invention relates to improved fluid-cooled electric discharge devicesand particularly to devices of this character adapted forhigh-frequency, high-power applications.

It is diicult to extend the power rating of high-frequency electricdischarge devices since the requirements that the lead-in inductance andinter-electrode capacities be kept small tend to result in a smallcompact structure. This makes it extremely difficult to dissipate theamount of heat that must be dissipated for higher power ratings. Inaccordance with an important aspect of my invention, I provide animproved highfrequency electric discharge device including a novelfluid-cooled grid electrode structure. My invention is an improvement onthe prior Elder and Crawford invention, described and claimed incopending application Serial No. 650,701, filed February 27, 1946, whichissued as U. S. Patent No. 2,489,872 on November 29, 1949.

It is an object of my invention to provide a new and improvedhigh-frequency electric discharge device.

It is another object of my invention to provide a new and improvedfluid-cooled electric discharge device.

It is a still further object of myinvention to provide an improvedduid-cooled grid electrode structure.

My invention will be better understood by reference to the followingdescription taken in connection with the accompanying drawing, and itsscope will be pointed out in the appended claims.

In the drawing, Figure 1 is an elevational view in section of anelectric discharge device embodying my invention; Figure 2 is asectional view taken along the line 2-2 of Figure 1; Figure 3 is anelevational view partially in section of a, modication of my invention,and Figure 4 is a sectional View taken along the line 4-4 of Figure 3.

Referring now to Figure 1 of the drawing, I have shown my inventionembodied in an electric discharge device of the transmitting type andincluding a generally cylindrical open ended anode I which together witha water jacket 2 forms a part of the envelope of the device. Asillustrated, the lower portion of the anode is provided with helical ns3 which define a plurality of cooling passages 4. These passagescommunicate with a header 5 at the lower end of the anode and with apair of chambers 6 and 1 provided between the upper portion of the anodeand the water jacket and communicating respectively with inlet andoutlet conduits 8 and 9. The chambers 6 and 'l do not communicate witheach other except through the spiral passages so that the fluid circuitincludes, in series, the chamber 6, certain of the spiral passages 4,the header 5, the remaining passages 4, and the chamber l. Asillustrated in the drawing, the water jacket is bonded to the lower endof the anode and is joined to the remainder of the envelope by areversely bent generally annular sheet-metal member I0 which is bondedat one end to the Water jacket 2 and at the opposite end is sealed to acylindrical glass wall member II. A second glass wall member I2 isjoined to the member Il by a cylindrical sheet-metal member I3 which issealed by the adjacent edges of the members II and I2. The member I3provides a support for the grid structure of the device designatedgenerally by the number I4 as Well as an externally accessible terminalfor the grid structure. A reinforcing terminal ring I5 is bonded to theexterior of the sheet-metal cylinder I3.

The remainder of the envelope is constructed to provide a pair ofconcentrically arranged terminals for the iilamentary cathode structure.As illustrated, a sheet-metal member I6 of generally annular shape andhaving a substantially U- shaped cross section in a radial plane,provides one terminal for the cathode as well as an end portion of thetube envelope. A second cathode terminal is provided by the solidcylindrical conductor l1 arranged within the annular member I6 andjoined to the inner edge thereof by a glass cylinder I8 which is sealedat one edge to the member l and at its opposite edge to a metal memberI9 bonded to the inner end of the terminal Il. The glass ring I8 andmember I9 together with the inner ange of the terminal member I 6provide a reentrant portion at the end of the tube envelope and themembers I6 and I'I provide concentrically arranged termipals andsupports for the cathode structure. As illustrated, in the drawing, acentrally arranged rod 29 is supported in a recess formed in the innerend of the central terminal I'I and is rigidly secured thereto. Asupport and terminal for one-half of the cathode elements are providedby a spider El supported in iixed relation. to the rod 2U at a pointadjacent the lower end oi the anode. In the particular embodimentillustrated, the cathode elements 22 are in the form of flat ribbons ofthin sheet nickel or si-. ilar materia-l which are coated on theexterior surfaces with a suitable mixture of alkaline earth oxides forimproving the electron emitting properties of the elements. As shown inFigure 2, the spider 2| has three equally spaced arms which are turnedupwardly at their extremities and are bonded to the cathode elements. Acathode supporting spider 23 is supported in spaced rela tion to thespider 2l and adjacent the free end of the centrally located rod 29.This spider is provided with six arms which are bonded to the upper endsof the cathode elements. rIhe lower ends of the remaining three cathodeelements are bonded to the arms of a third spider 23 which is supportedin fixed and electrically conducting relation with respect to theenvelope and terminal member I6 by sleeves 25 and 2t. The sleeve 26 isprovided with an outwardly directed fiange 2l which is bonded to theinner surface of the envelope wall I and with a conical portion 28 whichis bonded to the smaller sleeve 25.

' The upper filament supporting spider is urged upwardly by a lamenttensioning construction to maintain the filament under tension duringoperation. The spider is centered by a bearing member 29 of insulatingmaterial which slides on the rod and which is engaged by a metal sleeve30 surrounding the central supporting rod 29. The vsleeve 39 is in turnbiased upwardly by a compression spring 3l received within a recess 32lprovided in the inner end of the terminal Il and a motion transmittingstructure including washers 33 and 33 which are interconnected by aplurality (three in the illustrated embodiment) ofk rods 34. It will beapparent from the foregoing description that the cathode constructionjust described provides three parallel electrical paths between theterminals I6 and I'I with each path including two of the vcathodeelements 22 in series. In order to provide for eif'ective cooling of theseals lbetween the member I6 and the glass rings I2 and I8, a coolingblock and terminal 35 in the form of a cylinder is brazed to theenvelope Iwall I6. The cylindrical member `35 is provided with a coolingpassage 36 in proximity to the wall of the envelope.

VIn accordance with an important aspect of my invention, I provide animproved duid-cooled grid structure supported from the metal ring I3 ofthe envelope wall. As illustrated, in the drawing, the grid proper isprovided with a helically wound conductor 31 which is supported from thecylindrical terminal I3 by means of a generally cylindrical array offolded conduit 38 and a pair of supporting sleeves 39 and 40. The sleeve40 is bonded to the envelope terminal member i3 as provided with aninwardly directed flange 4I which supports the sleeve 39. The supportingand cooling structure provided by the conduit 38 is in the form of aplurality of series connected loops of conduit which `provide a circulararray of grid wire supports. The lower loop portions 42 arebentoutwardly at the lower ends thereof and are bonded to the innersurface of the tapered sleeve 39. The upper loops 43 are bonded to andprovide a support for a grid cap fifi. The free ends 45'and 46 of theconduit 38 are sealed through the terminal member I3 and provide eX-ternally accessible inlet and outlet fluid connections for the gridstructure.

It is apparent from the foregoing detailed description that the presentinvention provides for an adequately cooled system of electrodes in astructure which also provides for relatively short conductiveconnections with each of the electrodes so that the lead-in inductanceis minimized. The operation of a device embodying my invention,

as described above, indicates that a power output of 10 kilowatts at afrequency of 220 megacycles is readily obtained with a very compact tubestructure.

In Figures 3 and 4, I have illustrated a modiication of my inventionwhich is, as far as its general organization is concerned, similar tothat shown in Figures 1 and 2 and the same reference .numerals have beenapplied to the corresponding parts. In the modied form of my invention,the major difference is in the water-cooled grid electrode structure. Asshown in Figures 3 and 4, the grid conductor 31 is supported by awatercooled spider or hub 4'! which is bonded at its lower end to a gridsupporting sleeve 48. The sleeve 48 is in turn bonded to a flange member49 which is supported from the grid terminal sleeve I3 by a sleeve 40.As shown in Figure 4, the spider is provided with six radially extendingarms 47 which provide a circular array of supports for the grid wire. Awire 49 of nickel is inserted in the face of each of the radially eX-tending arms to provide a good bonding surface for the grid wire whichis tantalum, molybdenum or tungsten. The grid. structure is designed tobe iiuid cooled and is provided kwith an annular passage 59 near theupper end thereof ywhich communicates with a pair of conduits 5I and '52through longitudinal passages 53 and 54' formed in the body of thespider. As illustrated in Figure 4, the spider is provided with acentral passage 55 of sufficient size to allow clearance around thefilament tensioning structure. The spider is also recessed in thecentral portion of Athe lower end as shownL at 59 in Figure 3 to'accommodate the filament supporting spider 2| and the conduits 5I and`52.

Whilel' have shown and described a particular embodiment of myinvention, it will be apparent to those skilled in the art that manychanges and modications may be. made without departing from my inventionin its broader aspect, and I aim, therefore, in the appended claims tocover all such changes and modifications as fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A fluid-cooled grid electrode structure cornprising a cylindricalconductive sleeve forming a portion of an envelope wall and providing aneX- ternally accessible grid terminal, a conductive structure supportedfrom .said sleeveV including a second cylindrical sleeve of smallerdiameter than said first-mentioned sleeve and positioned in coaxialrelation with respect thereto, a conductive structure supported fromsaid second sleeve and providing a cylindrical array of supports for agrid conductor, a grid conductor wound upon said supports, saidconductive structure liavingpasr sages provided therethrough for coolingfluid and conduits extending through said first-mentioned sleeve andcommunicating with said passages to provide externally accessible inletand outlet iiuid connections.

2. A fluid-cooled grid electrode structure comprising acylindricalconductive sleeve forming a portion of an envelope wall, aconductive structure supported from said sleeve including a secondcylindrical sleeve of smaller diameter than said first-mentioned sleeveand positioned in coaxial relation with respect thereto, a conductivestruc-'- ture supported from said second sleeve and providing acylindrical array of supports, said conductive structure having passages'provided therethrough for cooling fluid and conduits ex'- tendingthrough first-mentioned sleeve and communicating with said passages toprovide externally accessible inlet and outlet fluid connections.

3. A uid-cooled grid electrode structure cornprising a cylindricalconductive sleeve forming a portion of an envelope Wall, a conductivestructure supported from said sleeve including a second cylindricalsleeve of smaller diameter than said first-mentioned sleeve andpositioned in coaxial relation with respect thereto, a conductivestructure providing a cylindrical array of supports extending Withinsaid second sleeve and secured thereto, said conductive structure havingpassages provided therethrough for cooling uid and conduits extendingthrough said first-mentioned sleeve and communicating with said passagesto provide externally accessible inlet and outlet uid connections.

4. A fluid-cooled grid structure including a conducting sleeve, acylindrical array of conduits joined together at opposite ends providinga series fluid path, a conducting sleeve surrounding one end of saidconduits and bonded thereto, a grid cap bonded to the other end of saidconduits, a second sleeve forming a part of the envelope and supportingsaid grid structure, and a pair of conduits sealed through said sleeveand connected with said conduits to provide externally accessible iluidconnections for said grid structure.

5. A fluid-cooled grid structure including a conducting sleeve, acylindrical array of conduits joined together at opposite ends providinga series fluid path, a conducting sleeve surrounding one end of saidconduits and bonded thereto, and a second sleeve forming a part of theenvelope and supporting said grid structure and a pair of conduitssealed through said sleeve and connected with said conduits to provideexternally accessible iiuid connections for said grid structure.

KENNETH C. DE WALT.

REFERENCES CITED The following references are of record in the ile ofthis patent:

UNTTED STATES PATENTS Number Name Date 2,020,428 Mouromtsefi" Nov. 12,1935 2,441,349 Eitel et al May 11, 1948 FOREIGN PATENTS Number CountryDate 474,933 Great Britain Nov. 10, 1937

